Honeywell 951WG-WH Stubby Recessed Magnetic Contact Switch (2 Pack) Save when you buy the 2 pack! 1 in. long magnet, it is ideal for casement windows, sliding windows and thin frame applications More powerful Alnico 8 magnet for up to 7/16 in. (11mm) gap Monitors the opening and closure of doors and windows Can be added to a wireless home security system with video surveillance cameras and more